This invention relates to an improved method of drawing wire and an improved wire drawing apparatus.
It is conventional practice to draw wire through a drawing die by wrapping the wire many times around a rotatable drawing block downstream of the die and using the engagement of the wire around the block to generate the drafting tension required for pulling the wire through the die. This method of drawing wire (hereinafter referred to as the capstan block method) has been widely used for many years and many different designs of apparatus for operating the method have been developed. To get adequate tension for drawing the wire through the die it is necessary to wrap the wire several times around the block and it has become conventional practice to extract from the wire the heat generated by the drawing process by cooling the wire while it is on the capstan block. The longer the dwell time of the wire on the block surface, the more effective the cooling can be and there has thus been a trend towards increasing the number of turns on the block and therefore also the size of the block beyond that necessary for traction purposes to meet the cooling requirement as drafting speeds increased. However, a large number of turns on each capstan block of a multiple die machine increases the complexity and cost of the machine and makes the threading up of the machine complicated and time-consuming.
In U.K. Pat. No. 1,249,926 (BISRA) it has been purposed to cool the wire while it is on the capstan block, by directly contacting it with liquid coolant sprays and in U.K. Pat. No. 1,428,889 (Kobe) it has been proposed to cool the wire as it leaves the drawing die by surrounding the wire with liquid coolant between the die and the capstan block.
In U.S. Pat. No. 1,918,237 (Alden), a multiple die wire drawing apparatus is disclosed in which a light finishing pass is provided by a driven grooved pulley interposed between the last die of the apparatus and the take-up reel, the wire being engaged by the groove of the driven pulley over an arc of less than 360.degree. subtended at the axis of the pulley.
This invention relates to a new concept in wire drawing methods and apparatus which combines direct wire/liquid coolant cooling and the use of a simple grooved wheel in place of a conventional capstan drawing block.
Preferred embodiments of apparatus in accordance with the invention are expected to be less expensive than equivalent capstan block apparatus, they are easier to operate and service and are capable of drawing wire with improved efficiency compared to capstan block apparatus.